Operators of electrical power networks monitor the state of their networks using sensors for voltage and current on cables in their networks. Such cables typically have an inner conductor, surrounded by an insulating layer, a shield layer, and an outer cable sheath. Normally, only a few sections of a cable are well accessible. It is therefore desirable that a sensor can be placed in any position along the cable length. Also, the installation of a sensor should be simple and quick, hence cost effective. For that purpose, sensors have been used that are protected by so-called cable splices. A typical cable splice comprises a sleeve that can be applied around a section of the cable. An example of such a sleeve is shown in the Japanese patent document JP60256068 (A), where a conductive or semi-conductive member is partially wound around an outer peripheral surface of the insulator of the cable to form a suspended electrode while a lead wire is embedded in said electrode and connected to it. Thereafter, an insulating member is wound around the outer peripheries of the suspended electrode and the insulator to cover both outer peripheral surfaces thereof. Both terminals of a shielding electrode, wound around the outer peripheral surface of the insulating member by using a semiconductive member, are wound around the outer periphery of the cable shielding layer in an overlapped state to connect both shielding electrodes.
A further, more advanced sleeve is described in the German patent publication DE 3702735 A1. In the device shown in this document, a conductive layer or conductive tape, located around the wire insulation of a high-voltage cable together with a low-voltage capacitor, forms a capacitive voltage divider. The voltage divider can be installed subsequently by a specially shaped connecting sleeve or by specially shaped cable terminations at any point in a cable network.
A voltage sensor for a power cable may require a plurality of electric or electronic components, like, for example, electrodes, wires, capacitors, transistors, resistors, inductors, wire coils, or integrated circuits. These components can be accommodated outside a sleeve, but being exposed outside the sleeve, these components may be damaged, affected by environmental conditions, experience short circuit, or may cause a risk of personal injury by an electrical shock. It would thus be desirable to arrange electric components in a manner that avoids these risks. It is further desirable to arrange the electric components in a mechanically stable and orderly manner, close to each other for facilitating electrical connections between them. The sleeve, that is to protect the cable in the section where a voltage sensor is installed, should furthermore be easy to apply to the cable.